I think it's hard to actually measure your soft skills, but I think you can measure the things that will help you improve your soft skills.

For instance you could improve your ability to communicate technical concepts via blogging - an easy metric there would be posting a certain number of blog posts. You can't really measure if your communication skill has increased, but I think the more you write, the more you will have practiced that communication skill and it should improve naturally.

For communicating with people in real life, you could also set a goal of talking to 3 people at every meetup you attend (that would have to wait until this whole COVID-19 thing is over!) Or maybe even giving talks at meetups, if that was something you were interested in.